Massive Power Usage Drop After Water Heater “Downgrade”

Jeremy S. Cook
Oct 28, 2019 · 4 min read

Several months ago, I wrote about how replacing your lights with LEDs could (theoretically) lead to massive power savings. Since then, I’ve been mostly disappointed in my power bill when compared to the same period last year. It’s been about the same, though this could be due to a number of factors, including a growing family, more actual lighting usage, or perhaps a difference in temperatures this summer.

However, I’m happy to report that my bill for September/October this year (9/20/2019 to 10/21/2019) was 434kWh, or 21% lower than a year ago. Because of the tiered pricing structure where I live, this meant a cost savings of $61.65, which I hope will continue in the months to come.

Water Heater Cost Driver

New water heater with snazzy stainless steel hoses

The big difference between this period and the last is that I got a new water heater after the previous unit started leaking. In addition to the new unit likely being more better insulated, it was also smaller at 60 gallons, versus the 100 gallon tank that we had before.

It appears that at some point between when the original tank was installed and now, these larger units became unavailable for home use. Rather than get an expensive commercial water heater unit, we installed a smaller 60 gallon tank on September 17th (with some hesitation). The good news is that I haven’t actually noticed a difference in the hot water whatsoever. The second piece of good news is that while I suspected there would be some power savings, $60 a month is well beyond what I’d hoped for. Hopefully this will continue into the future!

Calculation — 20% energy savings, even greater cost savings percentage-wise

Other Possibilities

To be fair, there are several things going on here that could play a role:

  • Kids are in school at least a few days a week, so perhaps lights are on less
  • Temperature variations for AC usage
  • I took a shower at the gym after working out a few times
  • LED lighting upgrades since last year

Power Monitoring

The other thing going on here is that for at least some period of time, my hot water heater was “insulated” by a water-soaked layer, as the inner tank was leaking. I have no idea how long this was going on, but if I had some sort of home energy monitoring hooked up that could pick out individual appliances — here’s one interesting idea that I haven’t tested— this would not only allow me to more instantly monitor usage and cost savings, but also alert me if something (like a water heater) is pulling more energy than is normal, thus indicating a problem.

In my case, the water heater was in the garage and the leak was slow, so no big deal. I just had it replaced soon after I figured out what was actually going on. In other cases (i.e. if the heater was inside the house) this could have been a real problem. Certainly something to consider.

Perhaps this is one reason why I didn’t notice any cost savings when I replaced the LED lights, as the heater was sucking more power. On the other hand, several months does seem like a long time for the insulation to be soaked before water spilled out onto the garage floor, so this being the cause is perhaps a bit of a long shot. Another argument for home energy monitoring it would seem.

Solar: Your Last Resort for Energy Savings

I can’t be the only one who looks forward to getting a monthly power bill

As long as we’re on the subject of energy savings, why not address the solar elephant in the room?

According to this site, the cost of solar in the US in 2019 comes out to $2.99 per watt, which we’ll round up to $3.00. Estimate you get 12 hours of full sunlight for 31 days per month (certainly generous), and you’re left with 372 watt-hours ==> .37kWh/$2.99 ==> .12kWh/$1 spent on solar each month. This equals out to be $.017/month in energy costs savings, or $.20/year in savings for each dollar invested.

This would then mean a payback of 5 years, which isn’t actually bad at all. Roughly estimating things another way based on a portion of the cost to install a system in Florida, and the estimated output in Miami gives somewhere around a 10 year payback at the higher energy cost above 1000kWh where I live.

This is probably more realistic, and doesn’t take into account an install potentially devaluing your house or causing roof damage. Also, as the technology continues to evolve with time there could always be something better that comes along.

Consider All Your Options

All this being said, between new light bulbs (linked previously) which theoretically pay for themselves in a few months, and a new water heater that was needed and will apparently pay for itself in a few years or less, at least for me there were better bargains to be found energy-wise. Solar may be a good option in many cases, but don’t get tunnel vision when trying to save money or power each month, be sure to look at all the options!

Note that power monitor link is to Amazon, and is affiliate.

Jeremy S. Cook

Written by

Engineer, tech writer, content creator, maker of random contraptions for fun and profit.

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